The production of semiconductor devices typically consists of forming or depositing a material on a substrate such as doped silicon. Typically, the processing requires annealing. The annealing can be performed as an equilibrium process in which an oven reaches the same temperature throughout, or a non-equilibrium process where the oven chamber is not itself heated. One example of a non-equilibrium process is a rapid thermal anneal (RTA), which can use high intensity lamps directed at a semiconductor wafer. With an equilibrium process, temperature measurement can be straight forward as the chamber temperature can be directly controlled, and is equal to the wafer temperature. With a non-equilibrium process it is generally necessary to use an indirect method of temperature control.
In order for such manufacturing processes to operate successfully, it is necessary to ensure that the annealing is performed at proper temperature. This is traditionally done through calibration of the annealing process. Various calibration methods have been used. However, no acceptable monitor has existed for measuring the temperature anneals such as the momentary titanium silicide transformation anneal, which ramps up to approximately 900.degree. C., then immediately ramps back down. This anneal is important for controlling silicide resistance and certain device parameters such as P-FET polysilicon depletion. Currently, a rough attempt to match tools can be made using boron implanted wafers. This method, however, lacks the resolution required to carefully match RTA tools or monitor the process for shifts over time.
The present invention is directed to overcoming the problems discussed above in a novel and simple manner.